Spectroscopic techniques using infrared (“IR”) radiation are known in the prior art and have been widely used for non-invasive measurement of the concentration of substances of interest in a body. One area of particular interest is the use of these techniques for the non-invasive measurement of the concentration of glucose and other constituents of the human bloodstream. Several patents and patent applications disclose methods to non-invasively measure the concentration of a substance, such as glucose, for example, in the bloodstream using infrared detection systems and methods.
U.S. patent application Ser. No. 12/883,063, filed Sep. 15, 2010 and entitled “Method for non-invasive analysis of a substance concentration within a body,” describes methods of measuring a concentration of a substance, such as glucose, in a body. The described methods include changing the temperature of the surface of a body from a first temperature to a second temperature, then changing the temperature of the surface of the body from the second temperature back to the first temperature. The method includes measuring a first amount of infrared (“IR”) radiation absorbed or emitted from the surface of the body in a first wavelength band and a second amount of IR radiation absorbed or emitted from the surface of the body in a second wavelength band at predetermined time intervals. The measurements occur during the time period that the temperature of the surface of the body changes from the second temperature back to the first temperature. A concentration of the substance may be determined based on the measurements. The contents of U.S. patent application Ser. No. 12/883,063 are hereby incorporated by reference in their entirety.